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Current microbial exposure models assume that microbial exchange follows a concentration gradient during hand-to-surface contacts. Our objectives were to evaluate this assumption using transfer efficiency experiments and to evaluate a model's ability to explain concentration changes using approximate Bayesian computation (ABC) on these experimental data. Experiments were conducted with two phages (MS2, Φ X174) simultaneously to study bidirectional transfer. Concentrations on the fingertip and surface were quantified before and after fingertip-to-surface contacts. Prior distributions for surface and fingertip swabbing efficiencies and transfer efficiency were used to estimate concentrations on the fingertip and surface post contact. To inform posterior distributions, Euclidean distances were calculated for predicted detectable concentrations (log 10 PFU cm -2 ) on the fingertip and surface post contact in comparison with experimental values. To demonstrate the usefulness of posterior distributions in calibrated model applications, posterior transfer efficiencies were used to estimate rotavirus infection risks for a fingertip-to-surface and subsequent fingertip-to-mouth contact. Experimental findings supported the transfer gradient assumption. Through ABC, the model explained concentration changes more consistently when concentrations on the fingertip and surface were similar. Future studies evaluating microbial transfer should consider accounting for differing fingertip-to-surface and surface-to-fingertip transfer efficiencies and extend this work for other microbial types.

Background: Halting the spread of harmful microbes requires an understanding of their transmission via hands and fomites. Previous studies explored acute and long-term care environments but not outpatient clinics. Objectives of this study were to track microbial movement throughout an outpatient clinic and evaluate the impact of a disinfectant spray intervention targeting high-touch point surfaces., Methods: At the start of the clinic day, a harmless viral tracer was placed onto 2 fomites: a patient room door handle and front desk pen. Patient care, cleaning, and hand hygiene practices continued as usual. Facility fomites (n = 19), staff hands (n = 4), and patient hands (n = 3-4) were sampled after 2, 3.5, and 6 hours. Tracer concentrations at baseline (before intervention) were evaluated 6 hours after seeding. For the intervention trials, high-touch surfaces were cleaned 4 hours after seeding with an ethanol-based disinfectant and sampled 2 hours after cleaning., Results: At 2, 3.5, and 6 hours after seeding, virus was detected on all surfaces and hands sampled, with examination room door handles and nurses' station chair arms yielding the highest concentrations. Virus concentrations decreased by 94.1% after the disinfectant spray intervention (P = .001)., Conclusions: Microbes spread quickly in an outpatient clinic, reaching maximum contamination levels 2 hours after inoculation, with the highest contamination on examination room door handles and nurses' station chairs. This study emphasizes the importance of targeted disinfection of high-touch surfaces., (Published by Elsevier Inc.)

Nosocomial viral infections are an important cause of health care-acquired infections where fomites have a role in transmission. Using stochastic modeling to quantify the effects of surface disinfection practices on nosocomial pathogen exposures and infection risk can inform cleaning practices. The purpose of this study was to predict the effect of surface disinfection on viral infection risks and to determine needed viral reductions to achieve risk targets. Rotavirus, rhinovirus, and influenza A virus infection risks for two cases were modeled. Case 1 utilized a single fomite contact approach, while case 2 assumed 6 h of contact activities. A 94.1% viral reduction on surfaces and hands was measured following a single cleaning round using an Environmental Protection Agency (EPA)-registered disinfectant in an urgent care facility. This value was used to model the effect of a surface disinfection intervention on infection risk. Risk reductions for other surface-cleaning efficacies were also simulated. Surface reductions required to achieve risk probability targets were estimated. Under case 1 conditions, a 94.1% reduction in virus surface concentration reduced infection risks by 94.1%. Under case 2 conditions, a 94.1% reduction on surfaces resulted in median viral infection risks being reduced by 92.96 to 94.1% and an influenza A virus infection risk below one in a million. Surface concentration in the equations was highly correlated with dose and infection risk outputs. For rotavirus and rhinovirus, a >99.99% viral surface reduction would be needed to achieve a one-in-a-million risk target. This study quantifies reductions of infection risk relative to surface disinfectant use and demonstrates that risk targets for low-infectious-dose organisms may be more challenging to achieve. IMPORTANCE It is known that the use of EPA-registered surface disinfectant sprays can reduce infection risk if used according to the manufacturer's instructions. However, there are currently no standards for health care environments related to contamination levels on surfaces. The significance of this research is in quantifying needed reductions to meet various risk targets using realistic viral concentrations on surfaces for health care environments. This research informs the design of cleaning protocols by demonstrating that multiple applications may be needed to reduce risk and by highlighting a need for more models exploring the relationship among microbial contamination of surfaces, patient and health care worker behaviors, and infection risks., (Copyright © 2018 American Society for Microbiology.)

Background: Study objectives were to track the transfer of microbes on soft surfaces in health care environments and determine the efficiency of an Environmental Protection Agency (EPA)-registered soft surface sanitizer in the health care environment., Methods: Soft surfaces at 3 health care facilities were sampled for heterotrophic plate count (HPC) bacteria, Staphylococcus spp, Streptococcus pyogenes, and Escherichia coli followed by a tracer study with a virus surrogate seeded onto volunteer hands and commonly touched surfaces. The occurrence of microbial contaminants was determined along with microbial reductions using the soft surface sanitizer. Soft surfaces were swabbed pre- and postintervention., Results: Tracer viruses spread to 20%-64% and 13%-41% of surfaces in long-term health care facilities and physicians' offices, respectively. Only 1 pathogen, methicillin-resistant Staphylococcus aureus, was recovered. The waiting room chairs had the highest concentration of HPC bacteria before disinfection (145.4 ± 443.3 colony forming units [cfu]/cm 2 ), and the privacy curtains had the lowest (39.5 ± 84.2 cfu/cm 2 ). Reductions of up to 98.5% were achieved with the sanitizer in health care settings and up to 99.99% under controlled laboratory conditions., Conclusions: Soft surfaces are involved in the spread of microbes throughout health care facilities. Routine application of an EPA-registered sanitizer for soft surfaces can help to reduce the microbial load and minimize exposure risks., (Copyright © 2018 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.)

Background: Recent scientific literature suggests that portable steam vapor systems are capable of rapid, chemical-free surface disinfection in controlled laboratory studies. This study evaluated the efficacy of a portable steam vapor system in a hospital setting. Methods: The study was carried out in 8 occupied rooms of a long-term care wing of a hospital. Six surfaces per room were swabbed before and after steam treatment and analyzed for heterotrophic plate count (HPC), total coliforms, methicillin-intermediate and -resistant Staphylococcus aureus (MISA and MRSA), and Clostridium difficile. Results: The steam vapor device consistently reduced total microbial and pathogen loads on hospital surfaces, to below detection in most instances. Treatment reduced the presence of total coliforms on surfaces from 83% (40/48) to 13% (6/48). Treatment reduced presumptive MISA (12/48) and MRSA (3/48) to below detection after cleaning, except for 1 posttreatment isolation of MISA (1/48). A single C difficile colony was isolated from a door push panel before treatment, but no C difficile was detected after treatment. Conclusion: The steam vapor system reduced bacterial levels by >90% and reduced pathogen levels on most surfaces to below the detection limit. The steam vapor system provides a means to reduce levels of microorganisms on hospital surfaces without the drawbacks associated with chemicals, and may decrease the risk of cross-contamination. [Copyright &y& Elsevier]

Background: Methicillin-resistant Staphylococcus aureus (MRSA) infections result in 19,000 deaths a year in the United States. Epidemiologic studies have shown that community-acquired infections are increasing dramatically, and strains typical of community infections are increasingly detected in hospital populations. Emergency medical responders (EMR) are exposed to both community and hospital MRSA patients, which, combined with their communal lifestyles in fire stations, results in higher risk of exposure. This study determined the occurrence and frequency of MRSA and other bacterial indicators on environmental surfaces in fire stations, training sites, and offices of EMR. Methods: Handled sponges were used for collection of targeted bacteria from commonly contacted environmental surfaces at EMR facilities. Biochemical tests confirmed isolates as S aureus, and MRSA was confirmed by growth on selective and differential media. An initial set of 500 samples was collected at 9 fire-related facilities to identify areas of increased exposure. Subsequent studies targeted sites (n = 160) for repeat sampling that were MRSA positive. Results: S aureus was isolated from 10.6% (17/160) of the sampled sites. The couch and the classroom desks were the most contaminated at 20% (4/20 and 2/10, respectively). Of the S aureus isolated, 64.7% (11/17) were confirmed as MRSA. Conclusion: EMR have a high potential for exposure to MRSA, not only through patient and hospital contacts but also in the fire station environment. MRSA was isolated with the highest frequency on the couches and the class desks. Although the true health significance of these exposures is unknown, improved infection control practices, such as routine handwashing and surface disinfection, are warranted to reduce MRSA exposures. [Copyright &y& Elsevier]